In this project Native American students will participate in-vivo and in vitro experiments to determine the influence of mast cells on tumor angiogenesis (the growth of new blood vessels) and metastasis. In-vivo experiments the angiogenic response and the metastatic rate in genetically mast cell-deficient W/Wv mice and their mast cell-sufficient +/+ littermates to subcutaneously growing B16BL6 tumors will be compared. In- vitro, the rate of cell outgrowth and the development of vessels which arise from rings of rate aorta cultured in collagen gels will be compared in the presence and the absence of B16BL6 tumor cells, mast cells, the tumor promoter, phorbol ester, and in conditioned media from B16GL6 tumor cells, mucosal mast cell, and connective tissue mast cells.